CN109232633B

CN109232633B - Combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane

Info

Publication number: CN109232633B
Application number: CN201811366609.5A
Authority: CN
Inventors: 丁冰; 梁秋鸿; 丁建峰; 杨静; 葛利伟
Original assignee: Jiangxi Chenguang New Materials Co ltd
Current assignee: Jiangxi Chenguang New Materials Co ltd
Priority date: 2018-11-16
Filing date: 2018-11-16
Publication date: 2020-12-25
Anticipated expiration: 2038-11-16
Also published as: CN109232633A

Abstract

The invention discloses a combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane, which comprises the following specific steps: adding methanol into trimethylchlorosilane, discharging generated hydrogen chloride from a system by using nitrogen, and absorbing into hydrochloric acid; and after the methanol is added, stirring for several minutes, transferring the mixed material into a high-pressure kettle, injecting liquid ammonia, stirring for reaction, filtering, recovering ammonia gas, collecting trimethyl monomethoxysilane by atmospheric distillation, and carrying out reduced pressure rectification to obtain hexamethyldisilazane. The method for jointly preparing trimethyl monomethoxysilane and hexamethyldisilazane realizes the economical efficiency of the production of trimethyl monomethoxysilane and avoids the use of organic alkali; improves the utilization rate of the trimethyl chlorosilane, and hardly generates hexamethyldisiloxane with lower economic value.

Description

Combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane

Technical Field

The invention relates to the field of organic synthesis, in particular to a method for jointly preparing trimethyl monomethoxysilane and hexamethyldisilazane.

Background

The trimethylsilyl group is a group with a unique structure, is commonly used as a protective group in organic synthesis, has extremely wide application in the organic silicon industry, can be used as a hydrophobic modified group of powder, and can also play an important role as an end capping group of silicon resin, silicon oil and silicon rubber. Industrially, main products having a trimethylsilyl group include trimethylchlorosilane, hexamethyldisiloxane, hexamethyldisilazane, and the like, and among them, trimethylchlorosilane is not generally used directly as a base material because of its high reaction rate, its release of hydrogen chloride, and the like. The hexamethyldisiloxane is simple to prepare, low in price, but low in reaction activity, can be used as an end-capping agent of silicone oil and silicone rubber, but is not widely applied to powder treatment. Hexamethyldisilazane is the most commonly used trimethylsilyl reagent for the hydrophobic modification of the powder at present, and has the characteristics of high end capping rate and good effect, but ammonia gas can be generated in the using process of the compound, odor is generated, and the rate of the end capping process is too high due to the catalytic action of ammonia, so that the reaction control is not facilitated. Compared with hexamethyldisilazane, trimethyl monomethoxysilane has better reaction activity, does not release gas, has no peculiar smell in the using process, does not need to absorb tail gas, is an ideal trimethylsilyl reagent, and shows good application potential and economic value. However, up to now, trimethyl monomethoxy silane has been difficult to be produced industrially completely, mainly because trimethyl monomethoxy silane is synthesized by esterification reaction of trimethyl chlorosilane and methanol, and the boiling points of trimethyl chlorosilane and trimethyl monomethoxy silane are almost the same, and trimethyl monomethoxy silane and methanol form azeotrope, which causes difficulty in separation, and these properties also cause that the esterification reaction is difficult to adopt tower type esterification, and a kettle type esterification reaction using organic base as a fluoacid agent is needed to obtain a target product with a certain yield, which results in high production cost. In addition, the water generated by the reaction of the methanol and the hydrogen chloride in the esterification process can cause the product to contain more hexamethyldisiloxane, so the economic value is low. These reasons have all greatly limited the commercial production and use of trimethylmonomethoxysilane. The development of a feasible industrial production method of trimethyl monomethoxysilane can purposefully solve the current problems and create good conditions for large-scale application of the good trimethyl silylizing reagent of trimethyl monomethoxysilane.

Disclosure of Invention

In order to overcome the defects in the prior art, a combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane is provided

The invention is realized by the following scheme:

a combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane comprises the following specific steps: adding methanol into trimethylchlorosilane, discharging generated hydrogen chloride from a system by using nitrogen, and absorbing into hydrochloric acid; and after the methanol is added, stirring for several minutes, transferring the mixed material into a high-pressure kettle, injecting liquid ammonia, stirring for reaction, filtering, recovering ammonia gas, collecting trimethyl monomethoxysilane by atmospheric distillation, and carrying out reduced pressure rectification to obtain hexamethyldisilazane.

The mass ratio of the methanol to the trimethylchlorosilane is 0.15-0.25.

The mass ratio of the liquid ammonia to the trimethylchlorosilane is 0.2-0.5.

The methanol and the trimethyl silicon chloride react under normal pressure, and the reaction temperature is between-30 ℃ and 10 ℃.

The reaction of the mixed material and liquid ammonia is carried out in a high-pressure kettle, the pressure in the high-pressure kettle is between 0.2MPa and 5MPa, and the reaction temperature is between 20 ℃ and 80 ℃.

The invention has the beneficial effects that:

the method for jointly preparing trimethyl monomethoxysilane and hexamethyldisilazane realizes the economical efficiency of the production of trimethyl monomethoxysilane and avoids the use of organic alkali; the utilization rate of the trimethylchlorosilane is improved, and hexamethyldisiloxane with lower economic value is hardly generated; substances such as trimethylchlorosilane and methanol which are difficult to separate from trimethylmonomethoxysilane are not left in the system after the reaction, the separation is simple, and the acquisition difficulty of the trimethylmonomethoxysilane with higher purity is reduced.

Detailed Description

The invention is further illustrated by the following specific examples:

the technical scheme of the invention is as follows: a combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane comprises the following specific steps: adding methanol into trimethylchlorosilane, discharging generated hydrogen chloride from a system by using nitrogen, and absorbing into hydrochloric acid; and after the methanol is added, stirring for several minutes, transferring the mixed material into a high-pressure kettle, injecting liquid ammonia, stirring for reaction, filtering, recovering ammonia gas, collecting trimethyl monomethoxysilane by atmospheric distillation, and carrying out reduced pressure rectification to obtain hexamethyldisilazane.

The mass ratio of the methanol to the trimethylchlorosilane is 0.15-0.25.

The mass ratio of the liquid ammonia to the trimethylchlorosilane is 0.2-0.5.

The chemical equation for the reaction of this application is:

the invention is further illustrated below with reference to specific examples:

example 1

Adding 200Kg of trimethylchlorosilane into a 500L reaction kettle, introducing cooling brine to reduce the temperature to-20 ℃, introducing nitrogen, adding 30Kg of methanol into the reaction kettle within 30 minutes, reducing the temperature in the kettle to-30 ℃, absorbing the generated hydrogen chloride into hydrochloric acid by using water, stirring for reaction for 15 minutes, then conveying the mixture into a 500L high-pressure reaction kettle through a pipeline, slowly adding liquid ammonia, observing the temperature of a reactant, introducing water to reduce the temperature when the temperature is higher than 80 ℃, stopping the temperature reduction when the temperature is lower than 20 ℃, adding 100Kg of liquid ammonia within 2 hours, stirring for reaction for 30 minutes, stopping the reaction, gasifying and recovering excessive ammonia in the liquid after the reaction for the next reaction, recovering a crude product of the ammonia, filtering, distilling at normal pressure, and collecting fractions with the boiling point of 55-58 ℃ to obtain 88Kg of trimethylmethoxysilane. And (3) putting the residual liquid into a reduced pressure rectification kettle, carrying out reduced pressure rectification, and collecting 45-55 ℃/50mmHg fractions to obtain 72Kg of hexamethyldisilazane.

Example 2

Adding 500g of trimethylchlorosilane into a 1L three-neck flask, cooling to 10 ℃ in an ice-water bath, introducing nitrogen into the flask for bubbling, starting stirring, slowly dropping 100g of methanol into a reaction kettle, reducing the temperature to be near 0 ℃ along with the reaction, taking out the generated hydrogen chloride by the nitrogen, continuing stirring for reaction for 10 minutes after the dropping of the methanol is finished, sending the mixture into a 1L stainless steel micro high-pressure reactor, inputting 100g of liquid ammonia into the reactor through a delivery pump at normal temperature, cooling the reactor by using cold water for 10 minutes, finishing the adding of the liquid ammonia, discharging the ammonia after the reaction is carried out in the high-pressure reactor for 120 minutes, removing excessive ammonia at normal pressure, filtering to remove ammonium salt, distilling at normal pressure, and collecting fraction with the boiling point of 54-58 ℃ to obtain 286g of trimethylmonomethoxysilane. And (3) carrying out reduced pressure rectification on the residual liquid, and collecting 35-40 ℃/30mmHg fractions to obtain 81g of hexamethyldisilazane.

Example 3

Adding 200Kg of trimethylchlorosilane into a 500L reaction kettle, introducing cold water to reduce the temperature to 10 ℃, introducing nitrogen, adding 50Kg of methanol into the reaction kettle within 30 minutes, gradually reducing the temperature in the kettle to-10 ℃, discharging generated hydrogen chloride out of the reaction system through the nitrogen, absorbing the hydrogen chloride into hydrochloric acid by using water, stirring for reacting for 15 minutes, sending the mixture into the 500L high-pressure reaction kettle through a pipeline, slowly adding liquid ammonia, controlling the temperature of reactants, introducing water to reduce the temperature when the temperature is higher than 80 ℃, stopping the temperature reduction when the temperature is lower than 20 ℃, adding 40Kg of liquid ammonia within half an hour, stirring for reacting for 30 minutes, stopping the reaction, recovering unreacted ammonia, filtering a crude product, distilling at normal pressure, collecting fractions with the boiling point of 55-58 ℃ to obtain 150Kg of trimethylmonomethoxysilane. And (3) feeding the residual liquid into a reduced pressure rectification kettle, and carrying out reduced pressure rectification and collection to obtain 19Kg of hexamethyldisilazane.

According to the method for simultaneously producing trimethyl-methoxy silane and hexamethyldisilazane, industrial production of trimethyl-methoxy silane is achieved, hexamethyldisilazane with the same high economic value can be produced, the total yield of two products is greatly improved compared with the prior art, and the commercial competitiveness of the products is improved.

Although the invention has been described and illustrated in some detail, it should be understood that various modifications may be made to the described embodiments or equivalents may be substituted, as will be apparent to those skilled in the art, without departing from the spirit of the invention.

Claims

1. A combined preparation method of trimethyl monomethoxysilane-hexamethyldisilazane is characterized by comprising the following specific steps:

adding methanol into trimethylchlorosilane, discharging generated hydrogen chloride from a system by using nitrogen, and absorbing into hydrochloric acid;

after the methanol is added, stirring for several minutes, transferring the mixed material into a high-pressure kettle, injecting liquid ammonia, stirring for reaction, filtering, recovering ammonia gas, collecting trimethyl monomethoxysilane by atmospheric distillation, and carrying out reduced pressure rectification to obtain hexamethyldisilazane; wherein the reaction of the mixed material and the liquid ammonia is carried out in a high-pressure kettle, the pressure in the high-pressure kettle is between 0.2MPa and 5MPa, and the reaction temperature is between 20 ℃ and 80 ℃.

2. The combined preparation method of trimethylmonomethoxysilane-hexamethyldisilazane according to claim 1, wherein: the mass ratio of the methanol to the trimethylchlorosilane is 0.15-0.25.

3. The combined preparation method of trimethylmonomethoxysilane-hexamethyldisilazane according to claim 1, wherein: the mass ratio of the liquid ammonia to the trimethylchlorosilane is 0.2-0.5.

4. The combined preparation method of trimethylmonomethoxysilane-hexamethyldisilazane according to claim 1, wherein: the methanol and the trimethyl silicon chloride react under normal pressure, and the reaction temperature is between-30 ℃ and 10 ℃.